Apparatus and method for detecting key signals in a mobile communication terminal
A method for detecting a key input signal in a mobile communication terminal is disclosed. The terminal has a plurality of keys constituting a key matrix structure with rows, columns, and a switch for connecting one of the rows to one of the columns, and including pull-up resistors for maintaining an input value of each row in the key matrix structure as a ‘high’ value. The method includes designating all ports connected to the rows and the columns as input ports; selecting one of a plurality of the columns, changing the selected column into an output port, and outputting a ‘low’ signal to the output port; scanning the keys; and changing a column selected after the key scan back into an input port.
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This application claims priority under 35 U.S.C. § 119 to an application entitled “Apparatus and Method for Detecting Key Signals in a Mobile Communication Terminal” filed in the Korean Intellectual Property Office on Oct. 18, 2004 and assigned Serial No. 2004-83210, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates generally to a user interface apparatus and method in a mobile communication terminal, and in particular, to an apparatus and method for detecting key input signals in a mobile communication terminal.
2. Description of the Related Art
A mobile communication terminal has been developed to enable its user to enjoy voice communication regardless of his or her location and movement. With the rapid progress of mobile communication technology, the mobile communication terminal has evolved into an advanced mobile communication terminal capable of providing data service in addition to voice service. Therefore, the user can acquire an increased volume of information using the mobile communication terminal. For example, the user can enjoy various services, such as short message service, data transmission/reception service and games service provided over the Internet using the mobile communication terminal.
In this way, the progress of mobile communication technology contributes to development of mobile communication terminals. For example, in order to transmit/receive a large volume of data, the mobile communication terminal should essentially include a high-capacity memory therein. In addition, the mobile communication terminal requires an interface device for transmitting the large volume of data to another apparatus, for example, a computer. Further, the mobile communication terminal supports a graphic user interface (GUI) in order to enable its user to enjoy various services such as Internet games and E-mail access using the mobile communication terminal. Moreover, there are various interface devices designed to enable the user to input commands to the mobile communication terminal or input text for E-mail.
Typically, a key matrix is used in enabling the user to input commands or texts to the mobile communication terminal. In addition, a touch screen or a touch pad can provide a user interface, but the key matrix is most widely used. Now, a description will be made of the key matrix used as a user interface.
A detailed description will now be made of the connection between the controller 111 and the key matrix circuit. The controller 111 is generally comprised of a single microprocessor. Further, the controller 111 includes terminals G-01 . . . G-14 . . . for recognizing corresponding key values. The terminals G-01 . . . G-14 . . . for recognizing key values by the controller 111 are commonly implemented with general purpose input/output ports. Rows and columns of the terminals G-01 . . . G-14 . . . are different from each other in operation. A description will be made of the terminals G-01 . . . G-14 . . . .
The terminals G-01, G-02, G-03 and G-04 connected to the rows are designated as input ports, and their initial values are set to ‘1’. In order to set the initial values to ‘1’, pull-up resistors R in the respective rows are connected to a power supply terminal Vcc. Because the pull-up resistors R are connected to the power supply terminal Vcc, the corresponding rows normally maintain a High state unless they are connected to the columns, so that the initial values are detected as ‘1’.
The terminals G-11, G-12, G-13 and G-14 connected to the columns are designated as output ports, and their outputs are set to ‘1’ when no scan is made. Only when it is checked whether there is an input of a specific key, i.e., whether the user presses a specific key, a terminal corresponding to the specific key outputs a value of ‘0’. The operation of checking whether there is a key input is referred to as a “key scan operation.” The key scan operation in the key matrix will now be described in detail with reference to
More specifically, when a value of ‘0’ is output via the terminal G-11 as stated above, one of the switches 121, 131, 141 and 151 located in the corresponding column can be input. If the user presses the switch 121 corresponding to the numeral 1, the switch 121 connects its column to its row. Because outputting a value of ‘0’ via the output terminal G-11 means that the output terminal G-11 is grounded, the terminal G-01 is also grounded, changing its value to ‘0’. That is, while all of the ports G-02, G-03 and G-04 have a High value as input values, the port G-01 receives a Low value. In this manner, the controller 111 can determine a key input value based on a combination of a column of G-11 and a row of G-01.
However, if the user inputs no key or does not input a key of a corresponding column, the controller 111 receives a value of ‘1’ from all of the ports G-01, G-02, G-03 and G-04.
In this method, the controller 111 can detect a key value input by the user through a combination of the corresponding column and row. After performing a key scan operation on one column in this way, the controller 111 performs a key scan operation on the next column in step 206. That is, before scanning the next column, the controller 111 selects the next column. After selecting the next column, the controller 111 can perform a key scan operation by repeating step 202 and its succeeding steps.
However, when the key matrix of
Assuming that, with respect to
Therefore, when the user simultaneously presses two or more keys or successively presses two different keys located in the same row very quickly, the controller 111 may fail to correctly detect the pressed keys. This problem inconveniences the user in using the mobile communication terminal.
SUMMARY OF THE INVENTIONIt is, therefore, an object of the present invention to provide an apparatus and method for correctly detecting a key value input by a user in a mobile communication terminal.
It is another object of the present invention to provide an apparatus and method for correctly detecting a key value input when a user simultaneously presses or successively presses keys located in the same row on key matrix logic in a mobile communication terminal.
It is further another object of the present invention to provide an apparatus and method for correcting detecting a key input value without modification of a key matrix structure in a mobile communication terminal.
To achieve the above and other objects, there is provided an apparatus for detecting a key input signal in a mobile communication terminal including a plurality of keys constituting a key matrix structure having a plurality of rows, a plurality of columns, and a switch for connecting one of the rows to one of the columns. The apparatus includes pull-up resistors for maintaining an input value of each row in the key matrix structure as a ‘high’ value; and a controller for connecting the columns and the rows to corresponding ports, designating the ports connected to the respective columns as input ports, designating the ports connected to the respective rows as input ports, and sequentially selecting the columns, thereby performing a key scan operation; and for changing a column selected during the key scan operation into an output port, outputting a ‘low’ value to the output port, and detecting a column to which the switch is connected among the columns connected to the rows, thereby detecting a key input signal.
To achieve the above and other objects, there is provided a method for detecting a key input signal in a mobile communication terminal including a plurality of keys constituting a key matrix structure having a plurality of rows, a plurality of columns, and a switch for connecting one of the rows to one of the columns, and including pull-up resistors for maintaining an input value of each row in the key matrix structure as a ‘high’ value. The method includes the steps of: designating all ports connected to the rows and the columns as input ports; selecting one of a plurality of the columns, changing the selected column into an output port, and outputting a ‘low’ signal to the output port; performing key scan by checking a plurality of the keys; and changing a column selected after the key scan back into an input port.
BRIEF DESCRIPTION OF THE DRAWINGSThe above and other objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which:
A preferred embodiment of the present invention will now be described in detail with reference to the annexed drawings. In the following description, a detailed description of known functions and configurations incorporated herein has been omitted for conciseness.
Mobile communication terminals that may be used with the present invention include cellular phones, PCS (Personal Communications Service) phones, smart phones, PDAs (Personal Digital Assistant), or any terminal with a key matrix structure. The “key matrix structure” refers to the structure illustrated in
The key matrix utilized in the present invention is similar in structure to the key matrix of
The controller 111 designates all ports G-01, G-02, G-03 and G-04 connected to respective rows as input ports, and also designates all ports G-11, G-12, G-13 and G-14 connected to respective columns as input ports to start. Peripheral circuits of the proposed key matrix are similar in structure to those of the conventional prior art key matrix. That is, the connection between the pull-up resistors R and the power supply terminal Vcc is included.
Next, a description will be made of a structure and operation of the key matrix in which the controller 111 designates its input ports and output ports in the manner described above.
Referring to
After outputting a value of ‘0’ to the column undergoing the key scan, the controller 111 checks all rows and determines whether there is an input key, in step 306. This will be described herein below by way of example. When a value of ‘0’ is output through the port G-11, if the user inputs no key, there is no row connected to the column corresponding to the port G-11. Therefore, input ports G-01, G-02, G-03 and G-04 of the respective rows all have a High value. However, if a key of numeral 1 is input, the switch 121 corresponding to the numeral 1 connects the port G-01 to the port G-11. In this case, because the key scan is performed using the port G-11, the port G-11 outputs a value of ‘0’, serving as a ground. Therefore, the port G-01 also serves as a ground, receiving a Low value. If a key of another column is simultaneously input together with the key of numeral 1, the corresponding port also receives a Low value as a key input.
Now, a description will be made of an operation performed when the user simultaneously inputs two or more different keys located in the same row or successively inputs the keys at high speed. It is assumed that key scan is performed on port G-11, and the 1 key and 2 key are pressed simultaneously. In this state, both the switch 121 corresponding to the 1 key and the switch 122 corresponding to the 2 key are connected. However, according to the present invention, port G-12 which is the column for 2 is an input port. Therefore, no value is output to port G-12. Because a ground value of ‘0’ is input to port G-11, the controller 111 can determine that numeral 1 is input. That is, the controller 111 can correctly detect the input value of key 1.
After checking a key input of the corresponding column, the controller 111 changes the selected column back into an input port in step 308. In this manner, it is possible to prevent errors from occurring because different values output from different columns are presented.
Thereafter, in step 310, the controller 111 selects the next column to be scanned. In doing so, the columns can be sequentially selected in the method described above, or according to a different order. After selecting the next column, the controller 111 can perform a key scan operation by repeating step 302 and its succeeding steps.
As can be understood from the foregoing description, the terminal having a key matrix structure according to an embodiment of the present invention can correctly detect a key input without error without modification of hardware logic.
While the invention has been shown and described with reference to a certain preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims
1. An apparatus for detecting a key input signal in a mobile communication terminal including a plurality of keys constituting a key matrix structure having a plurality of rows, a plurality of columns, and a switch for connecting one of the rows to one of the columns, the apparatus comprising:
- pull-up resistors for maintaining an input value of each row in the key matrix structure as a ‘high’ value; and
- a controller for;
- connecting the columns and the rows to corresponding ports, designating the ports connected to the respective columns as input ports, designating the ports connected to the respective rows as input ports, and sequentially selecting the columns, thereby performing a key scan operation; and
- changing a column selected during the key scan operation into an output port, output a ‘low’ value to the output port, and detect a column to which the switch is connected among the columns connected to the rows, thereby detecting a key input signal.
2. The apparatus of claim 1, wherein when the key scan operation on a particular column is completed, the controller changes the corresponding column back into an input port.
3. A method for detecting a key input signal in a mobile communication terminal including a plurality of keys constituting a key matrix structure having a plurality of rows, a plurality of columns, and a switch for connecting one of the rows to one of the columns, and including pull-up resistors for maintaining an input value of each row in the key matrix structure as a ‘high’ value, the method comprising the steps of:
- designating all ports connected to the rows and the columns as input ports;
- selecting one of a plurality of the columns, changing the selected column into an output port, and outputting a ‘low’ signal to the output port;
- performing key scan by checking a plurality of the keys; and
- changing a column selected after the key scan back into an input port.
4. The method of claim 3, wherein the step of performing key scan comprises checking an input key by detecting a change in voltage value input from a plurality of the columns.
Type: Application
Filed: Sep 2, 2005
Publication Date: Apr 20, 2006
Applicant: SAMSUNG ELECTRONICS CO., LTD. (Suwon-si)
Inventor: Sung-Wan Kim (Seoul)
Application Number: 11/219,190
International Classification: H03M 11/00 (20060101); H03K 17/94 (20060101);